The present invention relates to a fuel cell system in which a relief valve is provided in a fuel gas passage through which fuel gas typified by hydrogen gas flows.
As such a fuel cell system, there is conventionally known the one in which a and a fuel cell (see Japanese Patent Application Laid-Open No. 2002-134139 (Pg. 4 and FIG. 1), for example). This relief valve is mechanically opened when the fuel gas in the fuel gas passage is pressurized to a predetermined pressure or higher, and discharges the fuel gas from the fuel gas passage to the outside atmosphere.
Such a conventional fuel system is effective in terms of using the relief valve to prevent damage to the fuel cell and the system component, which is caused by abnormally increased pressure. However, after-treatments on the fuel gas discharged from the relief valve are not taken at all into consideration, hence the periphery of the discharge points may be changed to the atmosphere having high concentrations of the fuel gas.